Purpose	Command	Description
online man	link	official page
online man	link	official search
online man	link	die.net
online man	link	explainshell.com
online man	link	man.cx
online tutorial	link	geeksforgeeks.org
linux basic	man <tool>	Opens man pages for the specified tool.
linux basic	<tool> -h	Prints the help page of the tool.
linux basic	apropos <keyword>	Searches through man pages’ descriptions for instances of a given keyword.
linux basic	cat	Concatenate and print files.
system info	whoami	Displays current username.
system info	id	Returns users identity.
system info	hostname	Sets or prints the name of the current host system.
system info	uname	Prints operating system name.
system info	pwd	Returns working directory name.
network info	ifconfig	The ifconfig utility is used to assign or view an address to a network interface and/or configure network interface parameters.
network info	ip	Ip is a utility to show or manipulate routing, network devices, interfaces, and tunnels.
network info	netstat	Shows network status.
network info	ss	Another utility to investigate sockets.
processes info	ps	Shows process status.
system info	who	Displays who is logged in.
system info	env	Prints environment or sets and executes a command.
system info	lsblk	Lists block devices.
system info	lsusb	Lists USB devices.
system info	lsof	Lists opened files.
system info	lspci	Lists PCI devices.
linux users	sudo	Execute command as a different user.
linux users	su	The su utility requests appropriate user credentials via PAM and switches to that user ID (the default user is the superuser). A shell is then executed.
linux users	useradd	Creates a new user or update default new user information.
linux users	userdel	Deletes a user account and related files.
linux users	usermod	Modifies a user account.
linux users	addgroup	Adds a group to the system.
linux users	delgroup	Removes a group from the system.
linux users	passwd	Changes user password.
linux users	chage	change user password expiry information.
linux packages	dpkg	Install, remove and configure Debian-based packages.
linux packages	apt	High-level package management command-line utility.
linux packages	aptitude	Alternative to apt.
linux packages	snap	Install, remove and configure snap packages.
linux packages	gem	Standard package manager for Ruby.
linux packages	pip	Standard package manager for Python.
system info	systemctl	Command-line based service and systemd control manager.
processes	ps	Prints a snapshot of the current processes.
system info	journalctl	Query the systemd journal.
processes	kill	Sends a signal to a process.
processes	bg	Puts a process into background.
processes	jobs	Lists all processes that are running in the background.
processes	fg	Puts a process into the foreground.
network transfer	curl	Command-line utility to transfer data from or to a server.
network transfer	wget	An alternative to curl that downloads files from FTP or HTTP(s) server.
network service	python3 -m http.server	Starts a Python3 web server on TCP port 8000.
linux basic	ls	Lists directory contents.
linux basic	cd	Changes the directory.
linux basic	clear	Clears the terminal.
linux basic	touch	Changes file timestamps or creates an empty file.
linux basic	mkdir	Creates a directory.
linux basic	tree	Lists the contents of a directory recursively.
linux basic	mv	Move or rename files or directories.
linux basic	cp	Copy files or directories.
linux basic	nano	Terminal based text editor.
linux basic	which	Returns the path to a executable file or link.
linux basic	find	Searches for files in a directory hierarchy.
	updatedb	Updates the locale database for existing contents on the system.
linux basic	locate	Uses the locale database to find contents on the system.
linux basic	more	Pager that is used to read STDOUT or files.
linux basic	less	An alternative to more with more features.
linux basic	head	Prints the first N lines of STDOUT or a file.
linux basic	tail	Prints the last N lines of STDOUT or a file.
linux basic	sort	Sorts the contents of STDOUT or a file.
linux basic	grep	Searches for specific results that contain given patterns.
linux basic	cut	Removes sections from each line of files.
linux basic	tr	Replaces certain characters.
linux basic	column	Command-line based utility that formats its input into multiple columns.
linux basic	awk	Pattern scanning and processing language.
linux basic	sed	A stream editor for filtering and transforming text.
linux basic	wc	“word count”. Prints newline, word, and byte counts for a given input.
premissions	chmod	Changes permission of a file or directory.
permissions	chown	Changes the owner and group of a file or directory.